Thursday, January 26, 2012

I had this idea that I'm going to start interviewing folks on different technical topics via Skype or Google Hangout. Normally, I would use Cinelerra to perform this task, but for some reason, the recordings in Cinelerra showed some irritating sound artifacts. Testing in audacity showed no such audio problems. I'll bring this up on the Cin mailing list soon.

FFmpeg to the Rescue
So with Cinelerra not working for desktop recordings, I needed an alternate way to record my desktop screen as well as the audio from the person being interviewed. After some searching a good deal of trial and error, I found from the link in the reference section at the bottom of the page, a very nice ffmpeg command. You can save to any format you want. The example below shows how to save the microphone audio (hw:0,0) in PCM format. The desktop video is brought in via the xllgrab format specifier :ffmpeg -f alsa -i hw:0,0 -ac 2 -ar 48000 -acodec pcm_s16le -f x11grab -r 24 -s 1280x720 -i :0.0 -aspect 16:9 -vcodec libx264 -vpre lossless_ultrafast -threads 8 -y output.mov

Why Mule?

"Mules are not really stubborn. They can seem lazy because they will not put themselves in danger. A horse can be worked until it drops, but not so with a mule. The "stubborn" streak is just the mule's way of telling humans that things are not right. Mules are very intelligent and it is not a good idea to abuse a mule. They will do their best for their owner, with the utmost patience."About Mules